<!DOCTYPE html>
<html>
<head>
    <meta charset="UTF-8">
    <meta http-equiv="Content-Security-Policy" content="default-src 'self'; script-src 'self' 'unsafe-inline'; style-src 'self' 'unsafe-inline';">
    <title>加载中...</title>
    <style>
        body {
            margin: 0;
            padding: 0;
            display: flex;
            justify-content: center;
            align-items: center;
            height: 100vh;
            background-color: #f5f5f5;
            font-family: Arial, sans-serif;
        }
        .loading-container {
            text-align: center;
        }
        .loading-spinner {
            width: 50px;
            height: 50px;
            border: 5px solid #f3f3f3;
            border-top: 5px solid #3498db;
            border-radius: 50%;
            animation: spin 1s linear infinite;
            margin: 0 auto 20px;
        }
        .loading-text {
            color: #333;
            font-size: 18px;
        }
        @keyframes spin {
            0% { transform: rotate(0deg); }
            100% { transform: rotate(360deg); }
        }
    </style>
</head>
<body>
    <div class="loading-container">
        <div class="loading-spinner"></div>
        <div class="loading-text">正在加载应用...</div>
    </div>
</body>
</html>
